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CVE-2021-27851

Local privilege escalation in GNU Guix via guix-daemon and '--keep-failed'

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in v1.2.0-75109-g94f0312546
None on Exploit-DB, Metasploit or GitHub

Summary

A security vulnerability that can lead to local privilege escalation has been found in ’guix-daemon’. It affects multi-user setups in which ’guix-daemon’ runs locally. The attack consists in having an unprivileged user spawn a build process, for instance with `guix build`, that makes its build directory world-writable. The user then creates a hardlink to a root-owned file such as /etc/shadow in that build directory. If the user passed the --keep-failed option and the build eventually fails, the daemon changes ownership of the whole build tree, including the hardlink, to the user. At that point, the user has write access to the target file. Versions after and including v0.11.0-3298-g2608e40988, and versions prior to v1.2.0-75109-g94f0312546 are vulnerable.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • GNU Guix guix-daemon

    From v0.11.0-3298-g2608e40988; fixed in v1.2.0-75109-g94f0312546

References 2

guix.gnu.org

bugs.gnu.org